Iran will defend the regime of its regional ally Syria due to its anti-Israeli stance, supreme leader, Ayatollah Ali Khamenei told the visiting Turkish prime minister on Thursday.

"Iran will defend Syria because of its support for the anti-Zionist regime resistance," Khamenei said as he received Recep Tayyip Erdogan in the northeastern holy city of Mashhad, state television reported.

Turkish Prime Minister Recep Tayyip Erdogan on Thursday voiced his country's unwavering support for Tehran's nuclear ambitions in a meeting with Iran's President Mahmoud Ahmadinejad, according to an official statement.

"The government and nation of Turkey has always clearly supported the nuclear positions of the Islamic republic of Iran, and will continue to firmly follow the same policy in the future," Erdogan was quoted as saying in the statement issued by Ahmadinejad's office.

The U.N. and Arab League's envoy to mediate the Syria conflict, Kofi Annan, will visit Tehran next week, Iranian Foreign Minister Ali Akbar Salehi said on Wednesday.

"Kofi Annan is probably coming to Tehran on Monday," Salehi told reporters on the sideline of a visit by Turkish Prime Minister Recep Tayyip Erdogan.

Long-stalled talks between Iran and world powers are to be revived on April 13 at a place yet to be agreed, Iranian Foreign Minister Ali Akbar Salehi was quoted as saying on Wednesday by official media.

Salehi announced the date as he welcomed visiting Turkish Prime Minister Recep Tayyip Erdogan to Tehran for a two-day visit focusing on Iran's nuclear program and bilateral ties, the official Islamic Republic News Agency reported.

Turkish Prime Minister Recep Tayyip Erdogan arrived in Tehran on Wednesday for a two-day visit focused on talks about Iran's nuclear policy and ties, the official IRNA news agency reported.

Erdogan, who was greeted at the airport by Iranian Foreign Minister Ali Akbar Salehi, flew in from South Korea, where he had attended a nuclear security summit with other world leaders including U.S. President Barack Obama.

Turkey's former army chief Ilker Basbug went on trial Monday on charges of leading a terrorist group accused of plotting to overthrow the Islamist-rooted government, local media said.

Basbug, who was chief of staff from 2008 to 2010, has been in custody since January and risks life in prison if convicted in a case that has inflamed tensions between the government and the powerful military.

U.S. President Barack Obama and Turkish Prime Minister Recep Tayyip Erdogan agreed Sunday on the need to send "non-lethal" aid to Syrian rebels, including communications equipment, a U.S. official said.

The two leaders agreed that a "Friends of Syria" group meeting on April 1 should seek to provide such aid and also medical supplies, as they met in South Korea on the eve of a nuclear security summit, said U.S. deputy national security adviser Ben Rhodes.

Israel is using the Gaza Strip as a testing ground for a possible military strike on its arch foe Iran, the head of the radical Palestinian movement Hamas said on Monday.

"Israel is warming up the region for a possible war against Iran," Khaled Meshaal said in an interview with Turkey's Anatolia news agency.

Turkey on Friday "strongly" urged thousands of Turkish nationals to leave Syria and said it was considering withdrawing its ambassador from the violence-wracked country.

"Developments in Syria pose serious security risks for our nationals," the foreign ministry said in a statement. "Therefore it is strongly recommended that Turkish nationals currently in Syria leave and return home."

Hamas leader Khaled Meshaal arrived in Turkey on Friday to meet with Prime Minister Recep Tayyip Erdogan, who advocates cooperation with the Islamist movement, a close aid to the premier said.

"The prime minister will meet with Meshaal at 2:00 pm (1200 GMT)," the source told AFP on condition of anonymity.